In current practice 25 to 500 gallon chemical tanks with a pump are frequently staged at industrial sites and utilized to pump chemicals upon need. Frequently the sites are unmanned. As indicated in the “prior art” of FIGS. 1A-1D, such chemical tanks are typically supported on legs over a pan. A pump for the chemicals, as shown in the FIG. 1A, is typically located above the pan and under the tank. Gravity can at least assist the feed for the chemicals to the pump which can be electrically powered or gas powered.
The pan is provided so that any spill, as well as run-off rain that picks up chemicals leaking from orifices of the tank or pump, will be collected in the pan. Rain water is of particular concern in these circumstances as the rain that washes over the tank frequently becomes contaminated with leaking chemical. E.g. fittings installed not only on the tank but also around the pump and power lines and supply lines and gauge lines can leak at their seals.
Environmental issues are arising with these chemical tanks handled in accordance with the current practices. The issue is made more pressing when the tanks are located near urban areas and particularly when the tanks are unmanned. As mentioned above, a containment tank has fittings, such as for a chemical supply line and a sensor line, and chemicals can leak at these fittings over time. The pump can also leak chemicals at its seals. Rain washes the chemicals down into the pan, and although the potentially chemically laden rainwater that collects in the pan is in theory to be disposed of using proper procedures, unfortunately a drain in the pan may sometimes simply be pulled and the collected rainwater, contaminated or not, drained into the ground. Further, birds, animals and livestock may drink the contaminated water collected in the pan and become ill.
In particular in the oil and gas industry, and especially in regard to unmanned chemical tanks located near urban areas by such industry, the EPA is requiring tighter controls over the chemical tanks. Thus, it is desirable to improve the containment system for primary chemical tanks, in particular for tanks utilized for supporting pumping applications on pipelines, well heads, refineries and pulp and paper facilities. Most of these locations dictate unmanned operations, where an improved secondary containment system would be valuable to properly prevent all chemical spills and contamination.
One system developed in response to the animal problem mentioned above is illustrated in FIG. 1D. This system provides a porous lid (not clearly visible) over the pan. Chemically laden rain water drains through holes provided in the porous lid such that animals, livestock and birds cannot drink through the porous lid. A second alternate system proposes to minimize rainwater mixing with chemicals leaking from tank and pump seals by covering the tanks and pump with a tarp. Farm and industrial operations are known to utilize double walled tanks to contain primary tank leakage and spillage, but those systems do not address the problems of the contamination of rain water by leaks from a pumping mechanism. In sum, none of the prior art systems are totally satisfactory.
U.S. Pat. No. 6,149,026 to Manson teaches a secondary containment tank for enclosing a primary tank, and the inventor offers a remark about a possible provision for enclosing a pump. However, the containment system of Manson makes no provision for the treatment of power and chemical lines in and out of the system, especially as required by a pump, and the structure of the Manson system is unnecessarily expensive vis-à-vis the instant invention. The structure of the secondary and primary vessels of Manson are independent. Each Manson vessel provides self-sufficient, independent support. And the primary vessel has no portion exposed, for maintenance and convenience.
By contrast, the mating and nesting structure of the instant invention provides economies of construction cost and space while containing all leaks and spills from the primary container and the pump. (As “nesting” is used herein, two structures that “nest” when mated together exhibit enhanced structural strength, in excess of either structure alone.) The instant invention is comprised of at least one primary tank (preferably constructed essentially of one piece of plastic and designed to hold fluids such as petroleum products, chemicals or water solvents,) which primary tank sealingly mates with and nests within a secondary containment tank, preferably also constructed essentially of one piece of plastic, with a primary tank portion exposed. The nested construction permits economies of structure, space and cost, not possible with free-standing primary and secondary tanks. Provision is made for containing a pump, including utilizing a gravity feed.
A portion of the primary tank is exposed, preferably a primary tank lid portion. The secondary tank of the instant invention is preferably constructed to provide, in conjunction with portions of one or more primary tanks themselves, at least 110% chemical containment in the case of a primary tank rupture, as well as a containment housing for at least one pump. Fittings for lines are provided in and out of the secondary container above its 10% fluid containment level, to avoid issues of chemical leak at the secondary tank fittings and seals and thus the possible contamination of rainwater thereby.
The primary tank receives structural support and economy of space by significantly nesting within the secondary tank. In a preferred embodiment the secondary tank sealingly secures to and under a top portion of at least one primary tank. This construction permits the top or tops of the primary tank(s) to be accessible. The secondary tank is further designed to house the pumping mechanism(s), thus eliminating the risk of the contamination of rainwater by pump fittings, and preferably provides an access lid, sealingly mated to primary tank and/or the secondary tank portion.
The system of the instant invention significantly encloses at least one primary tank and pumping mechanism within a nested secondary container, protecting the surrounding environment from contamination by rainwater washing over chemicals leaking from fittings associated with either the primary tank or the associated pump as well as from spillage from a primary tank rupture. Preferably a portion of the primary tank(s) are exposed. A preferably unitary secondary tank component, together with primary tank portions, provides at least 110% containment for the primary tank fluids. Secondary tank fittings or openings are located above the 110% containment level of the primary tank liquid. In preferred embodiments rain water is inhibited from entering the secondary containment area by weather tight sealing between the secondary and primary tank(s) and the access lid.
The containment system of the instant invention is particularly useful to hold liquid for pumping applications in pipelines, well heads, refineries and pump and paper facilities. These locations are largely unmanned, and secondary containment is important to prevent chemical contamination of the environment, especially when the facilities closely interface with urban environments. Economies of material and cost and space arise with the nesting structure construction.